Improvement in piston-packings



dicated by the line :c w, Fig. 2.

UNITED STATES PATENT OFFICE.

WILLIAM R. THOMAS, OF CATASAUQUA, PENNSYLVANIA.

IMPROVEMENT lN PlSTON-PACKINGS.

Specification forming part of Letters Patent No. 46,733, dated March 7, 186%.

To all whom it may concern Be it known that I, WV. R. THOMAS, of Catasauqua, in the county ot' Lehigh and State of Pennsylvania, have invented a new and Improved Piston-Packing; and I do hereby deelare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the accompanying drawings, forming:part of this specification, in which-` Figure lis a section transversely through the piston-rod, the plane of section being in- Fig. 2 is a section in a direction parallel with the pistonrod, the line y y, Fig. l, indicating the plane of section. v

Similar letters of reference indicate like parts.

This invention relates to an improvement in that class of pistons in which steam is used to keep the packing-rings in contact with the inside surface of the cylinder.

The invention consists in the employment or use of a double shell fitting between the head and follower of the piston, and provided with a transverse partition connecting the two cylindrical shells and extending beyond'the outside shell toward the packingrings, in combination with two sets of secondary'packin g-rin gs w hich are separated from each other by said partition, and with holes in the piston-head and follower, and in the outside shell in such a manner that when steam is admitted either through the holes in the head or in the follower of the piston said steam will act upon the inner surface of the secondary packing-rin gs, and by its action the main packing-rings are forced steam-tight against the inner surface ofthe cylinder, and by the transverse partition of the double shell the passage of the steam from one side of the piston to the other is prevented.

A represents the cylinder of an ordinary steam-piston, which is cast solid with the (head B, and to which the follower C is secured by means of screws or in any other suitable manner. A double cylindrical shell, D

E, is fitted round the spider, its edges being ground steam-tight to the inner surfaces of the head and the follower, and the two shells D E are connected to each other by a transverse partition, a, which is situated at about -nular space b between said two shells in two equal parts, which are not in communication with each other.

The partition a extends beyond the outer shell, E, forming a iiange, c, as clearly shown in Fig. 2 of the drawings, and this flange separates the two sets of secondary packingrings F one from the other. These packing-rings act upon the main packing-rings G either direct or by interveningblocks, H, (in very large cylinders these blocks may be omitted,) and they are forced out by the action of the steam which is admitted through holes d c in the follower and head, and through holes lfin the outer shell, E.

The steam admitted through the holes d or c passes into the annular space b between the two shells, being prevented by the partition a from passing to the opposite or exhaust side of the piston, and it (the steam) acts on the secondary packing-rings F through the holes fin the outside shell, being'prevented by the flange c from passing round to the opposite side of the piston.

By the action of the steam on the secon dary rings F the main packing-rings G are held in close contact with the inside surface of the cylinder, all unnecessary friction is avoided, and the piston works tight without cutting.

The double shell D E, being made independent ofthe spider, can be removed with all its appendages and the entire piston can be made cheap and kept in order Without trouble or loss of time. l

It remains to remark that the number of secondary packing-rings on each side of the partition may be one or more, according to the size of the piston.

I claim as new and desire to secure by Letters Patent- The double shell D E, provided with holes f in the outside shell, and with a partition, a, and flange c, in combination with holes d e in the head and follower of the piston, and with secondary packing-rings F and main packing-rings G, all constructed and operating in the manner and for the purpose sub stantially as herein set forth.

VILLIAM R. THOMAS.

Witnesses:

DANIEL MILsoN, JOHN WILLIAMs. 

